Information extraction from thematic mapper data

The Landsat-4 spacecraft, launched on July 9, 1982, is equipped with a new electro-optical sensor expected to advance the remote sensing capabilities of Earth resources satellites. An experimental instrument, the thematic mapper (TM), provides data in seven discrete energy bands with greatly improved spectral, spatial and radiometric resolution, relative to previous Landsat satellite systems. Scientists at NASA, National Space Technology Laboratories (NSTL), Earth Resources Laboratory (ERL) conducted an evaluation of Landsat-4 TM data, soon after its launch, to examine the potential of this new electro-optical sensor for providing improved information for renewable resources and land cover studies. Investigations of TM data included forested wetland, urban and agricultural land covers using a scene of data collected over Arkansas and Tennessee on August 22, 1982. Standard digital information extraction techniques were employed, and the classification accuracies achieved with a single date TM data set exceeded a 90% correct confidence level. While only spectral analysis techniques were utilized for this initial evaluation, the results clearly indicate the improved performance provided by the experimental TM sensor over previous Earth observing capabilities.     

7. Dynamics,winds, circulation and turbulence in the atmosphere of venus

With the possible exception of the lowest one or two scale heights, the dominant mode of circulation of Venus' atmosphere is a rapid, zonal, retrograde motion. Global albedo variations in the ultraviolet may reflect planetary scale waves propagating relative to the zonal winds. Other special phenomena such as cellular convection in the subsolar region and internal gravity waves generated in the interaction of the zonal circulation with the subsolar disturbance may also be revealed in ultraviolet imagery of the atmosphere. We discuss the contributions of experiments on the Orbiter and Entry Probes of Pioneer Venus toward unravelling the mystery of the planet's global circulation and the role played by waves, instabilities and convection therein.     

Neural controllers for systems with unknown dynamics

This study presents a methodology for specifying a neural controller for a system about which no a priori model information is available. The neural design presumes that a finite duration input/output (I/O) histogram on the system is available. The design procedure extracts from the histogram sufficient information to specify the neural feedback controller. The resultant controller will drive the system along a general output reference profile (unknown during the design). The resultant controller also exhibits the capability of disturbance rejection and the capacity to stabilize unstable plants     

The Time Structure of Ground Level Enhancements in?Solar Cycle 23

In a recent paper McCracken et al. (J. Geophys. Res. 113:A12101, 2008) proposed that the Ground Level Enhancement (GLE) of 20 January 2005 may have been produced by more than one acceleration mechanism, with the first acceleration due to the solar flare and the second one due to the CME associated with that event. They also noted several other GLEs with similar multiple pulse structures. This paper systematically investigates all the GLEs of solar cycle 23, from GLE 55 on 6 November 1997 to GLE 70 on 13 December 2006, to study their morphology and pulse structure, and to determine whether the multiple structures that may be found in these events are qualitatively similar to that of the GLE of 20 January 2005. We use all the data of all NMs that saw each event, to have as much directional and spectral information as possible. It is shown that three of these 16 events do contain such double-pulse structures, and the properties of these three are discussed in some detail.